Spinnerette



May 5, 1964 J. P. MIKA ETAL SPINNERE'I'TE Filed Oct. 1'7, 1958 United States Patent 3,131,427 SPWNERETTE John P. Milra, Pearisburg, and Clarence E. Bishop, Narrows, Va, assignors to Celanese Corporation of America, New York, N.Y., a corporation of Delaware Filed Oct. 17, 1958, Ser. No. 767,806 3 Claims. (Cl. 18-8) The invention relates to the manufacture of artificial or synthetic filaments or fibers, and is more particularly directed to filaments of novel cross-section, and methods and means for making such filaments. Also, the invention relates to fabrics and other articles of manufacture, including non-textile products, of yarn or tow including such filaments in either continuous filament or staple form.

An object of the invention is to provide filamentary material affording a larger surface area than regular bulbous filaments for a given denier.

Another object of the invention is to provide filamentary material which because of its distinctive shape does not pack tightly and exhibits improved air permeability for its denier as compared with conventional filaments, thereby making the novel filamentary material particularly suitable for use in cigarette filters, as well as in upholstery, textile and carpeting applications.

A further object is to provide filamentary material of high abrasion resistance and smooth surface, thereby especially suited for use in carpet yarns.

Another object of the invention is to provide novel methods and means for the expeditious manufacture of the distinctively shaped filamentary material.

These, and other objects and advantages of the invention will be apparent from the following detailed description, taken in conjunction with the accompanying drawing in which:

FIG. 1 is a cross-section on an enlarged scale through filamentary materim produced in accordance with the invention;

FIG. 2 is a view of the face of a spinnerette having jet openings or orifices therein arranged to furnish filamentary material having the cross-section illustrated in FIG. 1;

FIG. 3 is a view of the face of a modified spinnerette;

FIG. 4 is a greatly enlarged cross-section through a yarn dry spun through the spinnerette of FIG. 3;

FIG. 5 is a view of the face of a spinnerette having openings therein to furnish a mixture or blend of filaments having the cross-section shown in FIG. 1 and filaments having a different cross-section;

FIG. 6 is a cross-section on an enlarged scale through the mixture of filaments produced by the spinnerette shown in FIG. 5; and

FIG. 7 is a view of a cigarette having a filter including the novel filamentary material.

Filamentary material made in accordance with the invention comprises, in cross-section, a pair of bulbous portions or lobes integrally connected in closely adjacent or abutting side-by-side relation. The bulbous portions have especially smooth, rounded contours, and except where connected to one another, they are substantially elliptical in shape. A channel extending lengthwise of the filament is located adjacent the area connecting the bulbous portions. Preferably, a pair of channels are provided on opposite sides of the filament, a channel being located on each side of the area connecting the bulbous portions. The Width of each of the channels, at its widest portion, is only a fraction of the total dimension of the filaments in a corresponding direction. The channels may possess substantial depth, with the total depth of both channels preferably greater than the height or corresponding dimension connecting the bulbous portions. The channels are continuous and extend unobstructedly throughout the length of the filament. The channels may be open to the exterior of the filament, or the filament may be of hollow character with one or both of the channels closed off from the exterior surface.

Filamentary materials in accordance with the present invention may comprise organic derivatives of cellulose such as the esters or ethers thereof, for example, cellulose organic acid esters such as cellulose acetate, cellulose propionate, cellulose butyrate, celluolse benzoate, cellulose acetate formate, cellulose acetate propionate, cellulose acetate butyrate, and the like, ethyl cellulose etc. The esters may be ripened and acetone-soluble, such as conventional cellulose acetate, or may be substantially fully esterified, that is, contain fewer than 0.29 free hydroxyl groups per anhydroglucose unit, e.g. cellulose triacetate.

The filament-forming material may also comprise other thermoplastic or solvent-soluble polymeric materials such as superpolyarnides e.g. nylon, superpolyesters such as polyethylene terephthalate, polyglycolic acid and cocopolymers thereof; acrylonitrile polymers and copolymers, polymers and copolymers of olefins and vinyl esters such as ethylene, propylene, vinyl chloride, vinylidene chloride, vinyl acetate, and the like.

The filament-forming material is initially in liquid phase, e.g. a solution of the filament-forming material in a volatile solvent is extruded through the jet openings of a spinnerette into an evaporative atmosphere, and the resulting filaments are preferably taken up at a linear speed of about to 700 and preferably 200 to 500 meters per minute. The take-up speed may range from about 0.6 to 1.4 and preferably 0.9 to 1.2 times the linear speed at which the solution is extruded through the jet openings. When dry spinning a solution of secondary cellulose acetate in acetone the temperature of the dope as extruded generally ranges from about 40 to C.

In making filamentary material of the configuration hereinbefore described, a novel form of spinnerette is used. The spinnerette is provided with jet openings arranged in groups, with the openings of each group so related to each other and of a contour to furnish components of a filament which, upon leaving the openings and still wet, fuse or coalesce with each other to form a finished filament having the described bi-lobed and channelled structure.

In greater detail and referring to FIG. 1 for one embodiment of the invention, the filaments 10 each comprise, in cross-section, a pair of bulbous portions 12, 12', which are integrally connected to each other at 14 in closely adjacent, side-by-side relation. As shown, the bulbous portions are each smooth, rounded, and generally elliptical in shape, the minor axis being somewhat smaller than the major axis. On each side of the connecting area 14, channels 16, 16 are provided. The channels are generally V-shaped with the sides thereof 18, 18' intersecting at the base 20. In most instances the channels are of substantial depth, and together have a total depth which may be approximately equal to the height or the parallel dimension of the connecting area 14. The channels are open to the exterior of the filament.

The sides 18, 18' of the channels furnish added surface areas so that for a given denier the described filament shape possesses a comparatively large surface area coupled with distinctive channels allowing the passage of air lengthwise of the filament. Such characteristics are particularly useful in cigarette filters, where low pressure drop, larger filter surface area and good bulk are desired. Also, due to the closely adjacent character of the connected bulbous portions, filaments of this cross-section 3 when made up into a bundle alone or with filaments of other cross-sections do not pack as tightly as conventional bulbous filaments. The filaments may be crimped in accordance with procedures well known in the art.

In making the filaments of cellulose organic acid esters, the usual system of dry spinning filaments of such composition may be used. Such dry spinning system for converting cellulose organic acid ester solutions into filaments is well known, and need not be illustrated or described in detail here. The spinnerette, however, is formed with a novel arrangement of opening or orifices.

As shown in FIG. 2, the filaments 10 are produced by a spinnerette 22 formed with pairs of openings A, one pair for each filament. While the spinnerette is shown as provided with three groups of openings, the number of groups may be as much as 300 or more. Openings 24 and 26 of each pair A, which are arranged in spaced relation in a single countersink with their straight sides 28 and 30 facing or opposite each other, are segments of closed conic sections, e.g. of circles or ellipses. In FIG. 2 the openings 24 and 26 are semi-circles of substantially the same size. They may, however, be of diiferent sizes. Also, the flat or straight sides 28 and 30 may be in parallel alignment, as shown, or slightly offset or out of parallellism in which latter event one of the resulting channels would be deeper than the other. The openings 24 and 26 of a pair are preferably formed by punching in one countersink.

When cellulose acetate in a volatile solvent is extruded through the openings 24 and 26 of a pair, two separate filament components are provided. The relationship of a pair of openings is such that immediately after extrusion, and before the evaporative atmosphere may dry or set the filament components these components merge and fuse with one another to form an individual or finished filament 10.

The denier of the individual filaments may be 55 or more but generally ranges from about 2 to 25 and preferably from about 3 to 16. Large bundles or tows of the filaments having the described configuration can be formed directly or preferably by combining several smaller bundles, such large bundles being especially useful for forming cigarette filters, for formation of staple fibers by cutting, etc. Prior to such further processing, the bundle of filaments may be subjected to treatment to increase its bulk, as by air jet bulking or crimping, e.g. to impart about 5 to 20 and preferably 7 to 12 crimps per inch.

FIG. 3 shows a modification in which a spinnerette 32 is provided with pairs of openings B, one pair for each filament to be produced. The openings 34, 36 of each pair are segments of a circle, but somewhat less than a full semicircle. The straight sides 38 and 40 of the openings are disposed to face one another. The straight sides, however, are out of parallelism, with the ends 42 and 42 closer to one another than the ends 44 and 44'. The openings, which are preferably punched in one countersink, are spaced with respect to one another so that the filament components extruded through each of the openings merges and fuse with one another to form the individual filaments 46, as shown in FIG. 4.

The filaments 46 each comprise, in cross-section, a pair of bulbous portions or lobes 48 and 5t integrally connected to each other in closely adjacent, side-by-side relationship by a comparatively thin cross web 52. The bulbous portions have smooth exterior surfaces and are substantially kidney-shaped. Channels 54 and 56 are located on each side of the filament, or adjacent the connecting web 52. The channels are of substantial height and surface area so that their total surface area may represent as much as 8% of the entire surface area of the filament.

Due to the olfsetting of the openings 34 and 36, offsetting in a sense that the straight sides 38 and 40 are out of parallelism as described, one or both opposite ends of the bulbous portions may be in contacting engagement absent.

so that a hollow channel or channels is provided between the area of connection 52 and such contacting ends.

In order to cause the filamentary material extruded through the two openings of each pair to merge, the shortest distance between the opposed straight sides of the openings should be less than 60% and preferably less than 50% of the length of the longer of such straight edges in the event that the straight edges are not of equal length.

It will be noted that while the peripheries of filaments 19 and 46 for the most part are approximately elliptical, the indentations result in far less mass than if they were This is most pronounced in FIG. 4 where it can be seen that the filament cross-section covers less than about 71% of the area of the smallest circle necessary to circumscribe it. In addition, the greater periphery means each filamment has a large surface area which improves its filtration efficiency without increasing the resistance to flow of smoke. Also, the merged shape gives substantially as great a moment of inertia as a full circle so that the resilience and resistance to deformation of the novel filaments are almost equal to those for round filaments which latter of course are of considerably greatter weight, greater apparent density, lesser surface area and greater resistance to air flow when bundled into a filter.

FIG. 5 shows a modification in which a spinnerette 60 is provided with openings 24 and 26 arranged in groups A, as well as with circular openings 62 which produce conventional filaments of regular bulbous cross-section. The cross-section of the resulting yarn seen in FIG. 7 shows a mixture or blend of filaments 10 and conventional filaments 64. The mixture or blend may comprise filaments 46 of the structure shown in FIG. 4, instead of the filaments 10. Also, instead of the conventional filaments 64, filaments of other cross-section, such as Y- or X-shape produced with jet openings of triangular or square contour, respectively, may be blended with the filament structures 10 or 46.

FIG. 7 shows a cigarette 70 including a filter 72 composed of p a large bundle of crimped filaments having a cross-section as hereinbefore described for the filament 10 or 46 disposed at one end of a tobacco filling 74 and Wrapped together therewith by a paper wrapper 7 6.

The following examples are included to illustrate the invention further:

Example I An acetone solution of secondary cellulose acetate, having an acetyl value of 55%, is extruded at a linear speed of 200 meters per minutes downwardly into a cabinet, through a spinnerette provided with pairs of semi-circular openings. The periphery of each opening lies on a radius of 0.045 mm., and the openings, which are related to each other as shown in FIG. 2, have their straight sides or faces spaced apart 0.08 mm. Air at room temperature is passed downwardly through the spinning cabinet. The resulting yarn is taken up at a linear speed of 200 meters per minute and has a denier of 750. 107 such tows are joined into a bundle and are passed through a stuffing box crimper to impart an average of about 8 crimps per inch. The tow is opened in conventional manner, sprayed with 6% of its weight of glycerine triacetate as a plasticizer and formed into a filter rod of 86,000 denier (taking into consideration the increase resulting from crimping). The rod is dried at room temperature for 2 hours to cause adhesion of the filaments at points of contact, in conventional manner, cut into 15 mm. plugs and wrapped with tobacco into filter-tipped cigarettes on conventional cigarette-forming machines.

Instead of using it in cigarette filters, the inditial 150 lament yarn can be air jet bulked for use in upholstery 0r carpet construction or it may be cut into high bulk p Preferably following crimping. Products made therefrom are characterized by good resistance to abra sion and S g and lay somewhat higher bulk than products made of equal denier regular cross-section filaments.

Example II The process of Example I is repeated substituting a spinnerette provided with 150 pairs of openings, each comprising a segment of a circle. The periphery of each opening lies on a radius of 0.060 mm., and the arc length is 0.150 mm. The openings, which are related to each other as shown in FIG. 4, have their straight sides or faces spaced apart 0.080 mm. at one end and 0.101 mm. at the other end.

In the spinnerettes shown in FIGS. 2 and 4, the openings of each of the groups A or B are all of substantially the same size. However, if desired, the openings of a group may differ somewhat in size, and the openings, though of the same general semi-circular shape, may be of different size from group to group so that in a bundle, the filaments having the integrally paired bulbous portions and the distinctive channelled construction as described may have difierent deniers.

It is to be understood that the foregoing detailed description is given merely by way of illustration and that many variations may be made therein without departing from the spirit of our invention.

Having described our invention, what we desire to secure by Letters Patent is:

1. A spinnerette having at least one pair of spaced jet openings for producing an individual filament, the openings each comprising a segment of a closed conic section with the straight sides facing each other, the shortest distance between opposed straight sides of the openings of each pair being less than 60% of the longer of said straight sides.

2. A spinnerette according to claim 1, wherein the straight sides are substantially parallel.

3. A spinnerette according to claim 1, wherein the straight sides are out of parallelism.

References Cited in the file of this patent UNITED STATES PATENTS 

1. A SPINNERETTE HAVING AT LEAST ONE PAIR OF SPACED JET OPENINGS FOR PRODUCING AN INDIVIDUAL FILAMENT, THE OPENINGS EACH COMPRISING A SEGMENT OF A CLOSED CONIC SECTION WITH THE STRAIGHT SIDES FACING EACH OTHER, THE SHORTEST DISTANCE BETWEEN OPPOSED STRAIGHT SIDES OF THE OPENINGS OF EACH PAIR BEING LESS THAN 60% OF THE LONGER OF SAID STRIAGHT SIDES. 